1. Field of the Invention
The present invention relates to the sterilization of barley malt and, more specifically, to a method that utilizes aqueous alcohol to destroy bacteria inherently present in barley malt, while retaining the desirable enzymatic activity thereof. The invention also provides a method for the preparation of a sterile barley malt flour having non-diminished enzyme activity.
The enzymatic activity of barley malt is well known for its industrial applications in starch-splitting and protein-degrading. In particular, barley malt is an important source of alpha and beta amylase, which are used in many foods, such as beer, wheat flour, and cereal to convert starch to fermentable sugars. Thus, it is essential in the sterilization of barley malt that the enzymes retain catalytic activity.
Barley is grown unprotected in open fields, and is inherently contaminated with soil bacteria and other micro-organisms. Barley malt is obtained by steeping, germinating and drying the barley kernel under conditions conducive to the development of such enzymatic activity. However, the moist conditions of the steeping operation, wherein the barley kernel is soaked in water for 3 to 5 days at 54.degree. F., also causes an enormous increase in the microflora. Although a high bacterial population is normal to the malting process and does not create a health hazard, aesthetically it is desirable to minimize the magnitude of their presence.
It is therefore desirable to sterilize, i.e., eliminate living microorganisms from, barley malt prior to use in food products and processes, without destroying enzymatic activity.
Heretofore, other microorganisms have been destroyed by physical agents, such as heat, or by chemical substances. However, prior art procedures employing sufficient heat to destroy bacteria also inactivate enzymes, such as amylase. Furthermore, most chemicals that have bactericidal properties, e.g., those capable of destroying bacteria, also destroy enzyme activity. Such chemicals suffer from the further shortcoming of not being permitted for use in food products either because they are irritating to humans when employed at effective bactericidal concentrations or leave behind toxic residues.
2. Description of the Prior Art
U.S. Pat. No. 3,992,147 discloses the use of isopropanol in combination with hydrogen peroxide to sterilize psyllium seed husk. U.S. Pat. No. 1,992,582 discloses a method of manufacturing rolled buckwheat or buckwheat flakes by mechanically removing the outer husk from buckwheat grains and then steaming the grains with water vapor either during or after treatment with one or more of protein coagulating reagents including certain organic acids such as acetic acid or alcohols, such as methyl, ethyl, or propyl alcohols. While such procedures have been effective in sterilizing buckwheat and preventing propagation of micro-organisms during storage, where continued enzyme activity is unnecessary, those skilled in this art have considered such elevated temperature sterilization to be detrimental to barley malt in that such steaming conditions are known to inactivate the enzyme system of barley malt.